This invention relates to rail-type electrification systems as used for vehicles, crane and the like, and more particularly to the rail constructions of such systems.
In the past a number of conducting rail and shoe constructions have been proposed, for rail-type electrification systems. Many of the rail constructions comprised electrically conducting rail members of rigid cross-section and characteristics, to which contact members have been affixed for engagement by the collector shoe. In one prior construction the conducting rail member had a deep V-shaped groove in its tracking portion, and a formed contact member of somewhat channel shape was fitted over the tracking portion, with the flanges of the contact member staked to the side walls of the conducting rail member. This arrangement was not especially satisfactory, since there was a tendency for the contact member to loosen and move with respect to the rail member under conditions of use, as when stressed or subjected to appreciable temperature changes, causing loss of conductivity.
Another prior construction was somewhat similar to the above described arrangement except that the contact member was perforated, and a welding procedure was utilized at the perforations, to secure the two members together. While this eliminated the looseness and relative movement of the members and improved the conductivity, it was an expansive procedure which increased the cost of the rail construction appreciably.
Yet another prior rail construction involved a rail member having a cross-section somewhat like an I-beam, where the contact member had a box-like cross-section, with its edge portions folded against the flanges or webs of the rail member. This arrangement also had the disadvantage that the contact member would swell and loosen, either as a consequence of stress or else temperature changes, causing loss of conductivity.
The above disadvantages of the prior devices were obviated by the composite rail construction described and claimed in my copending application, U.S. Ser. No. 403,939, filed Oct. 5, 1973 entitled Electric Feeder Rail Construction, now U.S. Pat. No. 3,902,579. While my identified rail construction proved to be satisfactory with regard to the aspects set forth above, it did not have metal guideways that would assure positive tracking of the collector shoe.